Chemical and Engineering News
February 13, 2012 (p37)
Researchers at the University of Cambridge have used supramolecular host-guest chemistry to fabricate cargo-carrying microcapsules from microfluidic droplets in a single step (Science, DOI: 10.1126/science.1215416). Oren A. Scherman, Chris Abell, and coworkers chose cucurbituril as the host molecule because it can form a ternary complex with two guests—in this case, methyl viologen attached to gold nanoparticles and a naphthol-containing copolymer. The researchers combined individual solutions of the three components in a microfluidic device to form a single aqueous phase. The oil phase shears droplets off the aqueous phase at a T junction. As the oil phase carries the droplets through a winding channel, the components combine to form hollow micro capsules consisting of a dispersion of gold nanoparticles in a polymer mesh held together by cucurbituril. The size of the microcapsules ranges from 10 to 24 μm and varies with the ratio of the oil and aqueous flow rates. The researchers can load a variety of cargo—such as drugs, biological molecules, and even cells—in the microcapsules by adding a fourth solution to the aqueous phase during fabrication.
Post type: quote
Cambridge University Research News
11 February 2012
A new, single-step method of fabricating microcapsules, which have potential commercial applications in industries including medicine, agriculture and diagnostics, has been developed by researchers at the University of Cambridge. The findings are published Friday (10 February) in the journal Science.
The ability to enclose materials in capsules between 10 and 100 micrometres in diameter, while accurately controlling both the capsule structure and the core contents, is a key concern in biology, chemistry, nanotechnology and materials science.
Currently, producing microcapsules is labour-intensive and difficult to scale up without sacrificing functionality and efficiency. Microcapsules are often made using a mould covered with layers of polymers, similar to papier-mâché. The challenge with this method is dissolving the mould while keeping the polymers intact.
Now, a collaboration between the research groups of Professor Chris Abell and Dr Oren Scherman in the Department of Chemistry has developed a new technique for manufacturing ‘smart’ microcapsules in large quantities in a single step, using tiny droplets of water. Additionally, the release of the contents of the microcapsules can be highly controlled through the use of various stimuli.
The microdroplets, dispersed in oil, are used as templates for building supramolecular assemblies, which form highly uniform microcapsules with porous shells.
The technique uses copolymers, gold nanoparticles and small barrel-shaped molecules called cucurbiturils (CBs), to form the microcapsules. The CBs act as miniature ‘handcuffs’, bringing the materials together at the oil-water interface.
“This method provides several advantages over current methods as all of the components for the microcapsules are added at once and assemble instantaneously at room temperature,” said lead author Jing Zhang, a PhD student in Professor Abell’s research group. “A variety of ‘cargos’ can be efficiently loaded simultaneously during the formation of the microcapsules. The dynamic supramolecular interactions allow control over the porosity of the capsules and the timed release of their contents using stimuli such as light, pH and temperature.”
The full report can be found in Cambridge University Research News.
The AQDOT technology has been published in Science.
Science 10 February 2012:
Vol. 335 no. 6069 pp. 690-694
One-Step Fabrication of Supramolecular Microcapsules from Microfluidic Droplets
Jing Zhang, Roger J. Coulston, Samuel T. Jones, Jin Geng, Oren A. Scherman, Chris Abell
Although many techniques exist for preparing microcapsules, it is still challenging to fabricate them in an efficient and scalable process without compromising functionality and encapsulation efficiency. We demonstrated a simple one-step approach that exploits a versatile host-guest system and uses microfluidic droplets to generate porous microcapsules with easily customizable functionality. The capsules comprise a polymer-gold nanoparticle composite held together by cucurbituril ternary complexes. The dynamic yet highly stable micrometer-sized structures can be loaded in one step during capsule formation and are amenable to on-demand encapsulant release. The internal chemical environment can be probed with surface enhanced Raman spectroscopy.
Received for publication 18 October 2011.
Accepted for publication 18 January 2012.
The Food Navigator
Nathan Gray, 10-Feb-2012
An innovative new technology platform could provide manufacturers and food formulators with greater control and speed when producing encapsulated ingredients such as flavours and bioactive ingredients, say its developers.
The new technology – a single-step method for producing ‘smart’ microcapsules using fluid droplets – is said to have potential commercial applications in food, nutrition, and pharmaceuticals, among others. Developed by researchers at the University of Cambridge, UK, and published in prestigious academic journal Science, the team behind the new technology promises that the ‘one-step’ microcapsules offer several advantages over currently used techniques.
Speaking with FoodNavigator.com, Dr Oren Scherman from the department of chemistry at Cambridge explained that the fluid technology used by the new platforms means that microcapsules have little variation in terms of size, and are “highly reproducible and scalable.” “I think that the fundamental advance that we have taken is the ability to both formulate the capsule and encapsulate cargo in a single step, so all the molecules and components are dynamically assembled simultaneously,” said Scherman, who was one of several researchers from the University of Cambridge involved in the platform’s development.
“We have on demand capability for release, and you can also have whatever you want as far as capsule size, or cargo, all in a uniform structure,” he said, noting that he was sure that there was “a lot of opportunity within the food manufacturing and production domain.”
“Because it’s a platform technology, it has a lot of applicability to many diverse areas, and I think that is something we are keen to explore through contact current leaders in the field,” added the expert.
The full report can be found in The Food Navigator.